Possible deviations from the O(4) limit of the vibron model in diatomic molecules

Abstract A U (3)↔ O (4) transitional description of diatomic molecules in the U (4) vibron model is considered. The analysis includes the U (3) and O (4) limits of the theory. Applications to vibrational-like band-heads of several diatomic molecules indicate that there are significant deviations from the O (4) limit of the theory.